A device for cleaning stirrer tanks is known, for example, from German patent specification No. 2,307,609. In this case the stirrer tank is an upright tank upon which a stirring apparatus is positioned which is connected with a drive motor. In order to mount the stirring apparatus, the upright tank is provided on its upper side with a connection piece which engages in a base structure which is secured to said upper side and which includes a horizontally extending flange. An electrically driveable flange motor with a hollow drive shaft is screwed to the flange of this base structure. A hollow shaft supporting at its lower end the stirring tool, e.g. an impeller, a propeller or the like, is guided through the hollow drive shaft, penetrates a seal mounted on the tank in the connection piece or even therebelow and is nonrotatably connecting with the hollow drive shaft via an abutment, a flange coupling or the like. The hollow shaft supporting the stirring tool has on its lower end wall a spray nozzle whose jets are directed onto the bottom of the tank. Moreover, spray nozzles whose jets act on the inner jacket surface of the stirrer tank are also located in a specific spaced relation on the hollow shaft inside the stirrer tank.
Such a cleaning device is capable of adequately cleaning the inner surface of the stirrer tank, but it is a fact in the dairy industry, for instance, that most of the deposits or residues form on the stirring apparatus and in the area of the seal which guides the hollow shaft through the upper tank wall. These deposits are fairly difficult to remove, particularly since they are not included as part of the normal tank cleaning operation.
In addition, the nozzles themselves require cleaning and replacement at times which, however, is only feasible in most cases when the stirring apparatus has been removed from the tank or when the hollow shaft for the cleaning medium supply has previously been driven out of the hollow drive shaft, it then being possible to remove the drive motor and to maneuver the hollow shaft out of the manhole in the stirrer tank. It has been found, however, that in these known blending or stirring devices, the hollow shaft has frequently seized or is so corroded in the hollow drive shaft that it can no longer be removed from the hollow drive shaft. In such a case, there is usually no other recourse than to cut off the hollow shaft for the stirring tool drive, to provide a new drive motor and to weld a new stirring shaft stump on to the hollow shaft. Such repair work is therefore not only costly, but also results in long interruptions of operation (down-time) so that hitherto known mixing and stirring devices have not been satisfactory.
The object of the invention is therefore to further develop the known device for cleaning stirrer tanks using further features of the class mentioned in the first paragraph at the outset in such a way that deposits on the stirring tool, in the sealing area of the hollow shaft and on the nozzles can be eliminated with simple and economically feasible measures.
This object is accomplished in principle in that the upper and lower sides of said stirring tool and the area on the inside of the seal which guides the hollow shaft through the tank wall or upper end wall are acted upon by the spray means by the cleaning medium which is supplied under pressure, and that the hollow shaft is mounted so as to be easily removable from the drive shaft in order to clean the spray means.
These measures ensure a cleaning oven even of those parts of the stirrer tank which are affected by deposits especially during operation and which were hitherto inaccessible without special and costly measures. Of course, the customary arrangement of spray nozzles can be retained which simultaneously act on the sidewall, the bottom and the top wall of the stirrer tank.
In particular, the design is such that the end of the hollow shaft which faces the tank bottom is releasably closed by a spray nozzle or a nozzle head which directs the cleaning medium onto the lower side of the stirrer tool. Such a spray nozzle or such a spray head has correspondingly directed nozzle apertures so that the entire bottom side of the stirring tool is certain to be cleaned by the cleaning medium.
The same action can be achieved for the entire stirrer tool in that the end of the hollow shaft facing the tank bottom is closed to the cleaning medium and bores, and nozzles or the like are disposed in the hub of the stirring tool formed by an impeller, propeller or the like in such a way that the jets of cleaning medium act on the upper and lower sides of the impeller, propeller or the like.
Furthermore, it is provided that a least two diametrically opposed, downwardly directed spray nozzles or spray heads which penetrate the wall or the cylinder jacket of said hollow shaft are provided to act on the upper side of the stirrer tool only. Such an arrangement is adequate when an impeller, for example, which serves as the stirrer tool has only two vanes. If more vanes exist, a corresponding additional number of spray nozzles are provided in the hollow shaft.
Another arrangement is characterized in that a ring of spray nozzles or spray heads directed onto the area on the inside of the seal is disposed below the seal which guides the hollow shaft through the tank wall. The arrangement of the nozzles can also be arbitrary. What is important is that the area facing the stirrer tool of the seal guiding the hollow shaft through the container wall is included and acted upon intensely by the cleaning medium.
In a device for cleaning stirrer tanks comprising a hollow shaft for supplying the cleaning medium which penetrates the hollow drive shaft of the drive motor and which is upwardly supported therein, the embodiment is designed such that the hollow shaft is nonrotatably mounted in the end of the hollow drive shaft facing away from the stirrer tank by means of a flange sleeve which is designed to have an external conical taper toward its free end and is adapted to be pressed into the corresponding conical hollow end of the drive shaft on the flange side by means of a threaded nut adapted to be screwed onto the hollow shaft and to nonrotatably interconnect the hollow shaft with the hollow drive shaft in cooperation with the abutment upwardly supporting said hollow shaft. Serving as the abutment, the lower end of the hollow drive shaft on the inside and the proximate portion of the hollow shaft for the cleaning medium have a conical design such that, after the flange sleeve has been loosened at the upper end of the drive shaft, the hollow shaft can be easily withdrawn or driven out of the drive motor.
Since the flange sleeve can be loosened without difficulty in case of necessity, for example for cleaning the spray nozzles, the mounting designed in accordance with the invention thus facilitates not only convenient assembly, but in particular rapid disassembly of the hollow shaft as well and thus shorter interruptions of operation. These advantages are attained at a very low cost so that the complete and comprehensive cleaning of a stirrer tank is now extraordinarily economical to carry out. In addition, due to the conical abutment and the externally conical flange sleeve, the hollow shaft is centered exactly relative to the hollow drive shaft when the threaded nut which can be screwed on the hollow shaft is tightened so that smooth running of the hollow shaft is ensured.
It is self-evident that it is unimportant in the inventively designed mounting of the hollow shaft in the hollow drive shaft whether an auxiliary medium for the material to be stirred in the stirrer tank, for example, is introduced through the hollow shaft instead of a cleaning medium. Since the above-explained mounting of the hollow shaft has the same importance in all these cases, independent protection will be claimed for the hollow shaft mounting in the hollow drive shaft.